Theology is the study of God. Theology is important because knowing God is important. CS Lewis had this to say in Mere Christianity:

I remember once when I had been giving a talk…an old, hard-bitten officer got up and said, “I’ve no use for all that stuff. But mind you, I’m a religious man too, I know there’s a God, I’ve felt Him: out alone in the desert at night; the tremendous mystery. And that’s just why I don’t believe all your neat little dogmas and formulas about Him. To anyone who’s met the real thing they all seem so petty and pedantic and unreal!”

Now in a sense I quite agree with that man. I think he probably had a real experience of God in the desert. And when he turned from that experience to the Christian creeds, I think he really was turning from something real to something less real. In the same way, if a man has once looked at the Atlantic from the beach, and then goes and looks at a map of the Atlantic, he will also be turning from something real to something less real.

…But here comes the point. The map is admittedly only colored paper, but …. it is based on what hundreds and thousands of people have found out by sailing the real Atlantic. In that way it has behind it masses of experience just as real as the one you could have from the beach; only, while yours would only be a single isolated glimpse, the map fits all those different experiences together. In the second place, if you want to go anywhere, the map is absolutely necessary. As long as you are content with walks on the beach, your own glimpses are far more fun than looking at a map. But the map is going to be more use than walks on the beach if you want to get to America.

Now, Theology is like that map. Merely learning and thinking about Christian doctrines, if you stop there, is less real and exciting than the sort of thing my friend got in the desert. Doctrines are not God: they are only a kind of map. But that map is based on the experiences of hundreds of people who really were in touch with God, experiences compared with which any thrills or pious feelings you and I are likely to get on our own are very elementary and very confused.

And secondly, if you want to get any further, you have to use the map. You see, what happened to that man in the desert may have been real, and was certainly exciting, but nothing comes of it. It leads nowhere. There is nothing to do about it. In fact, that is just why a vague religion — all about feeling God in nature, and so on — is so attractive. It is all thrills and no work; like watching waves from the beach. But you will not get to Newfoundland by studying the Atlantic that way, and you will not get eternal life by simply feeling the presence of God in flowers or music.